The proposed study will be aimed primarily at providing new information and insight into the interrelations between oxidative metabolic reactions and the transport of ions against electrochemical gradients. The kinetics of the intracellular response of the respiratory chain to changes in transport rate will be measured especially carefully, in the expectation that this type of information will lead to a better understanding of the overall process. Manipulation of electrochemical gradients, inhibitor studies and variations in metabolic substrates will be used to clarify enzyme mechanisms directly and indirectly involved in active transport. Although it is not primarily the aim of this project to provide a detailed picture of the energetics of active transport in thermodynamic terms and quantities, nevertheless relevant data will result and be published. Instead the emphasis will be on making optical observations on intracellular events (redox potential and pH changes) and on interpreting these data in terms of interrelations between transport mechanisms and oxidative metabolism.